Volume 19 Issue 4

The sulfate process for bamboo pulp production encounters silicon interference during the pulping stage, necessitating desilication before the alkali recovery section. This study investigated the desilication of bamboo pulping black liquor (BPBL), demonstrating that silicon was removed effectively by adding Mg/Al compound desilication agent to the BPBL via burning at high temperature. The desilication extent can reach 84% when the desilication agent is added in the proportion of Mg/Al (magnesium sulfate and sodium metaluminate) in the ratio 1.25:0.75. Subsequently, less-silicon white mud (LSWM) can be prepared after black liquor (BL) combustion desilication. LSWM was compared with normal WM as a blank sample, and the morphology and physicochemical properties of two kinds of WM were characterized. X-ray diffractometry revealed that both types of WM are primarily composed of calcite crystalline CaCO₃ and hydrated CaSiO₃. Scanning electron microscopy, X-ray photoelectron spectroscopy, and particle size analysis demonstrated the reduced content of CaSiO₃ generated in the LSWM. This result indicated that the Mg/Al compound desilication agent removed the silicon from the green liquor (GL), thereby reducing the residual silicon in WM. This reduction is beneficial to the calcination recovery and comprehensive utilization of WM.

Low nutrient use efficiency (NUE) of conventional chemical fertilizers has resulted in the loss of costly nutrients and related environmental implications. Consequently, enhancing crop productivity and nutrient use efficiency are major challenges. In this backdrop, a field experiment was conducted to study the impact of pine oleoresin (POR) and neem oil (NO) coated urea (CU) fertilizers on crop productivity and nutrient recovery efficiency in maize-wheat cropping system grown on Vertisols of central India. The treatment combinations were POR-CU and NO-CU at 100% and 75% of recommended doses of fertilizers (RDF); normal urea (100% RDF); and an unfertilized control. Two years results indicated that the increment in grain yields due to POR-CU and NO-CU applications were 18.8% and 11.7% for maize and 11.6% and 3.49% for wheat, respectively, over normal urea. The apparent recovery efficiency of N (RE_N) for POR-CU, NO-CU, and normal urea at 100% RDF were 65.8%, 64.2%, and 51.4% in maize and 43.2%, 37.0%, and 34.6% in wheat, respectively. There was no significant difference noticed between POR-CU and NO-CU with respect to grain yield and N recovery efficiency. Hence, the study suggested that POR-CU could be a possible alternative option to NO-CU for improving crop yield and NUE. However, further research is needed to determine how effective POR-CU is in diverse agricultural systems and climatic conditions.

Mechanical properties and behaviors of bamboo joined by different connections were considered in this work. Makino bamboo (Phyllostachys makinoi) culms from Taiwan were used as the connection material to explore the form of cross-lap joints. Since the cross-lap joint is a common joint in bamboo structures, the mechanical properties of tension, slip, and rotation were evaluated for three types of joints: lashing joint, iron wire joint, and steel bracket joint, under different load conditions. The results showed that the ultimate load of bamboo culms under lateral partial compression has a positive correlation with the number of bamboo nodes and the relative distance to the base-section of the bamboo culms. The mid-sections and end-sections have similar uniaxial compressions in the transverse orientation. According to results of tensile testing, the tensile stiffness of the three joint types is as follows in descending order: iron wire joint, lashing joint, and steel bracket joint, with the reverse order for ultimate load testing. In terms of slip testing, the withstanding of ultimate loads and increases in slip stiffness can be attributed to bamboo nodes that assist in creating slip stiffness in lashing joint. However, ultimately, steel bracket joints hold the highest slip stiffness. Our findings for rotation stiffness value show the following tendency: steel bracket joint > lashing joint > iron wire joint.

The concentrations of Sr, Tl, and V in soils and plant organs were evaluated at a copper mining site. These are heavy metals that are extremely dangerous and harmful to human and environmental health and, therefore, are on the ATSDR substance priority list. Within the scope of the study, soil samples were taken from different soil depths in the spoil area, the rehabilitation area where planting was performed and adult trees that were at least 20 years old, and the forest area. Soil samples were taken from the rehabilitation and forest areas where Pinus nigra Arnold., Pinus sylvestris L., and Robinia pseudoacacia L. species grow, and leaf, bark, wood, and root samples were taken from trees in the same areas. The study evaluated variations in heavy metal concentrations in soils based on species and soil depth and in plants based on plant species and organs. The study found that the heavy metal concentrations in soils and plant organs generally varied depending on plant species, while these variations were insignificant depending on soil depth. The highest concentrations by species were generally obtained for Sr in Robinia pseudoacacia and for Tl and V in Pinus nigra.

The durability of small-diameter larch wood was studied with respect to its treatments with wood tar and wood vinegar in three environments—underground, underwater, and outdoors—for 53 months. This study involved assessing wood cell wall deterioration using optical microscopy, X-ray computed tomography imaging, and X-ray diffraction, along with evaluating various physical and mechanical properties using Korean standards. Severe deterioration was observed in vinegar-treated sapwood after being buried underground. Collapsed cells were often found in untreated and wood vinegar-treated wood buried underground. Noticeable decreases in the physical and mechanical properties were observed in the sapwood of wood vinegar-treated wood buried underground. The wood tar-treated wood buried underground remained relatively intact with minimal changes in its physical properties. No significant degradation was observed in the wood discs submerged in water, and there was no difference in density, shrinkage, hardness, and shear strength between the untreated and preserved wood submerged in water. Under outdoor conditions, wood vinegar-treated wood showed less degradation of the wood discs than untreated and wood tar-treated wood. In conclusion, wood tar enhanced the durability of the wood when it was buried in soil, whereas the wood vinegar treatment provides an advantage when exposed to outdoor conditions.

The present research aimed to increase the accuracy of predicting the maximum force required to compress a solid cardboard box. Changes in the technology of solid cardboard production and the design of packaging help to increase the durability of packaging; however, typical estimation methods do not take these changes into account. By determining the number of important parameters of the box and using a specific approach, it was possible to develop a semiempirical model of the maximum force that compresses the box and simplifies its description. By using this model, the amount of solid board required for a specific package can be reduced without reducing the life of the box. The maximum force prediction method is also suitable for creating other box models at different moisture levels.

This research aimed to determine the impact of the mechanical densifying process of wood material on the varnish surface adhesion strength. Specimens from black pine (Pinus nigra) and Uludag fir (Abies bornmuelleriana Mattf.) were subjected to densification in a hydraulic press at 140 °C to the extent of 25% and 50% in the radial direction. While densification increased the surface adhesion strength of the varnish layer in black pine, the value decreased in fir. Regarding the interaction between densification ratio, surface treatment, and wood type, the highest surface adhesion strength of the varnish layer was found in black pine + unsanded surface + 25% densification, and the lowest was in Uludag fir + unsanded surface + 50% densification. It can be stated that the densification process creates high adhesion values for the polyurethane varnish in the black pine wood type. The sanding process has an intensifying effect on these values, and the products that were obtained from the polyurethane varnished samples do not require sanding. Considering these situations can provide significant advantages in projects with wood materials subjected to the densification process.

Thermal modification is a process capable of improving properties affecting wood performance, such as biological durability. This study aimed to assess the potential of thermal modification in enhancing the resistance of Couratari sp. wood to deterioration by Trametes versicolor, Nasutitermes corniger, and Cryptotermes brevis. Five treatments were analyzed, represented by the untreated and thermally modified wood at 180, 190, 200, and 210 °C. The wood’s chemical composition and resistance to biodeterioration in laboratory tests were evaluated. Thermal modification, especially at 210 °C, altered the chemical composition and increased the wood’s durability class against the fungus. However, the process did not affect termite attack. There was a significant positive correlation between corrected mass loss and hemicellulose and total extractive contents, as well as mass loss caused by T. versicolor and lignin and hemicellulose contents. The use of thermal modification in 190 °C is recommended for Couratari sp. wood due to its enhanced biological durability, with 210 °C being particularly effective.

China has abundant straw resources; however, the utilization of straw waste resource remains challenging. In this work, corn straw fiber and corn straw ash were applied to concrete as raw material after pretreatment. Through mechanical and thermal conductivity tests, it was concluded that the tensile strength of the corn straw fiber was 160.5 MPa after alkali treatment. The corn straw fiber and corn straw powder did not enhance the compressive strength of concrete. Compared with original concrete, the thermal conductivity of concrete added with 1.5% corn straw powder decreased by 25.9%, and the thermal conductivity of concrete with 5% corn straw ash was reduced by only 5.2%. Through thermogravimetric analysis of the concrete, it was found that the internal weakly bound water and strongly bound water will be lost in the range 100 °C to 160 °C, Ca(OH)₂ will decompose from 420 °C to 500 °C, and CaCO₃ will decompose approximately at 800 °C. It is recommended that corn straw powder and corn straw ash can be added at 1.5% and 5% concentrations to ensure that the mechanical properties can meet the engineering requirements and achieve good insulation performance.

In this study, the importance of the materials and designs used in aircraft furniture is considered, and products are recommended for material selection for sustainable aircraft interiors. The type of composite material produced from waste paper, a type of material that has never been used in aircraft before, has potential as a material choice that can be used in the aviation industry in terms of its contribution to recycling, cost, lightness, and water resistance. Conditions such as flammability, durability, compatibility with other materials and lightness of the materials used in aircraft equipment are important, and some alternative material options have been evaluated.